The LCD (Liquid Crystal Display) possesses advantages of thin body, power saving and no radiation to be widely used in many application scope. Most of the liquid crystal displays on the present market are back light type liquid crystal display devices, which comprise a liquid crystal display panel and a back light module. The backlight module provides light sources for the liquid crystal display panel. The liquid crystal display panel controls the throughput of the light in advance with signal driving. With the color resists, the light passing through is filtered to be red, green, blue, three primary colors. With the adjustment and match for the light intensities of the three primary colors, the display of different brightness and colors are realized.
FIG. 1 is a sectional diagram of a liquid crystal display panel according to prior art. FIG. 2 is a solid exploded diagram of the liquid crystal display panel in FIG. 1. As shown in FIG. 1 and FIG. 2, the liquid crystal display panel comprises a CF substrate 100, a TFT substrate 200 oppositely located to the CF substrate 100, a liquid crystal layer 300 located between the CF substrate 100 and the TFT substrate 200, an upper polarizer 400 located above the CF substrate 100, a lower polarizer 500 located under the TFT substrate 200 and a border adhesive (not shown) at a border position between the CF substrate 100 and the TFT substrate 200; the CF substrate 100 comprises a glass substrate 110, a color resist layer 120 and a black matrix 130 located on the glass substrate 110 and photospacers 140 being located above the black matrix 120 and corresponding to the black matrix 120; the TFT substrate 200 comprises a glass substrate 210, a TFT layer 220 located on the glass substrate 210 an alignment film 230 located on the TFT layer 220.
The working procedure of the liquid crystal display panel is to control the twists of the liquid crystal molecules in the pixel area with the voltages of the TFT substrate 200 and the CF substrate 100 for correspondingly changing the polarization state of the transmission light. In cooperation with the upper polarizer 400 and the lower polarizer 500 at two sides of the TFT substrate 200 and the CF substrate 100, the objective of controlling the transmission light volume can be achieved; the CF substrate 100 is to filter and absorb the light passing through the liquid crystal layer 300 to make that the light in each pixel area after exiting the liquid crystal display panel is constructed by three primary colors (or four colors).
However, the CF substrate 100 can only allow the light of partial wavelengths passing through, and the upper polarizer 400 is necessary to polarize the light. Thus, the intensity of the light passing through the CF substrate 100 will decay to be about 33% of the original intensity, which is one of the reasons why the LCD light efficiency is lower.
With the development of technology and the demands of the customers, high requirements is proposed to the light filtering ability of the color filter film for chasing the higher display quality. However, the color expression capability faces bigger restrictions because of the limitations of the frequency spectrum of the backlight source and the properties of the color resist material itself. The arisen organic light emitting material and quantum dot (QD) have great advantages in the light illumination aspect. According to the theory of the quantum restriction, the wavelength of the designated quantum dot is uniquely identified at the specific size, and the property of the structure determines that the frequency range of the emitting light is extremely narrow, and the full width at half maximum (FWHM) can reach up to 20 nm. By manipulating the synthesis dimension of the material, the emitting lights of RGB, three different frequency ranges can be obtained. By utilizing the excellent light emitting property of the quantum dot, the optimization to the emitting light spectrum can be realized to obtain high color gamut display and high color purity, which provide great helps for promoting the display performance.